The present technique relates to a display panel including a light emitting element, such as an organic EL (Electro Luminescence) element, and so on, for example, for each pixel, and to a display apparatus and an electronic system including the display panel.
In recent years, in a field of display apparatuses for displaying images, developments have been made on display apparatuses using a current-driven light emitting element, which changes luminance in accordance with a flowing current value, such as an organic EL element, for example, as a light emitting element of a pixel. And product commercialization of the apparatuses is in progress. The organic EL element is a self-luminous element unlike a liquid crystal element, and so on. Accordingly, in a display apparatus using organic EL elements (organic EL display apparatus), a light source (backlight) is not necessary, and thus compared with a liquid-crystal display apparatus that necessitates a light source, it is possible to make the apparatus thinner and brighter.
Incidentally, in general, a current-voltage (I-V) characteristic of an organic EL element deteriorates with passage of time (deterioration with time). In a pixel circuit in which an organic EL element is driven by current, when an I-V characteristic of the organic EL element changes with time, a change occurs in a division ratio between an organic EL element and a drive transistor connected to the organic EL element in series, and thus a gate-source voltage of the drive transistor also changes. As a result, a value of the current flowing through the drive transistor changes, and a value of the current flowing through the organic EL element changes, thereby changing luminance in accordance with the current value.
Also, a threshold voltage (Vth) or mobility (μ) of a drive transistor sometimes changes with time. Also, the Vth and the μ sometimes changes for each pixel circuit in accordance with variations in production process. When the Vth or the μ of a drive transistor changes for each pixel circuit, a value of the current flowing through the drive transistor varies for each pixel circuit. Even if a same voltage is applied to the gate of the drive transistor, luminance of the organic EL elements varies, and thus uniformity of the screen is lost.
Thus, even an I-V characteristic of an organic EL element changes with time, or Vth and μ of a drive transistor changes with time, in order to keep the luminance of the organic EL element at a certain value without being affected by those changes, developments are being made on a display apparatus in which a correction function on variations of the I-V characteristic of the organic EL element and a correction function on variations of the Vth and the μ of the drive transistor are incorporated (for example, refer to Japanese Unexamined Patent Application Publication No. 2008-083272).